The present invention is in the field of clutch bearings, of the type comprising a rolling bearing mounted on an operating member equipped with at least one cylindrical part. The operating member is actuated mechanically or hydraulically to displace the bearing axially so that it acts via its rotating race on the diaphragm of a clutch and thus operates it.
The invention relates more specifically to clutch bearings in which a self-alignment elastic member is arranged between the non-rotating race of the clutch thrust rolling bearing and the operating member supporting the said thrust bearing.
French document No. 2 755 487 is known and describes a clutch bearing comprising a rolling bearing equipped with a rotating race and with a non-rotating race and mounted on an operating member equipped with a cylindrical part and with a radial flange against which the non-rotating race of the bearing bears, a member for elastic self-alignment of the non-rotating race with respect to the operating member being arranged around the cylindrical part of the operating member and in axial contact with the non-rotating race. The elastic self-alignment member comprises a means of bearing axially against the non-rotating race and a means of axial and radial securing to the cylindrical part of the operating member, the said bearing and securing means being separate from one another. The self-alignment member comprises a radial portion in which there are axially flexible elastic tabs bearing against a radial portion of the non-rotating race, and a ring of catching tabs extending inwards from the radial portion and axially on the opposite side to the elastic tabs. In the mounted state, the catching tabs exert, on the cylindrical part of the operating member, an inwardly-directed radial force which, through a bracing effect, prevents any axial movement of the self-alignment member away from the non-rotating race.
As a certain radial clearance remains between the bore of the non-rotating race of the bearing and the operating element, the thrust bearing can self-align with respect to the clutch diaphragm if the axes of these two parts are not initially coincident, self-alignment then being maintained through axial frictional contact of the radial surfaces of the non-rotating part and of the flange of the operating element, even if the thrust bearing is no longer in contact with the diaphragm or when contact is with a light preload.
While such a device is satisfactory in numerous instances, it can cause certain problems, particularly when very little space remains in the axial direction between the frontal radial parts of the rotating race and of the non-rotating race. What happens then is that it is no longer possible for the self-alignment element to be arranged, even partially, between the two races in the axial direction. Furthermore, it is not conceivable to produce a narrow passage or a rubbing seal in the radial direction, in that radial displacement between the rolling bearing and the operating element is possible.
The invention proposes to solve these problems.
The invention proposes a very compact self-centring device which furthermore provides excellent frontal sealing for the thrust rolling bearing, this sealing maintaining its entire effectiveness independently of the radial displacement of the rolling bearing with respect to the operating element when the bearing is self-centring.
The clutch bearing, according to one aspect of the invention, is a device of the type comprising an actuating element intended to be mounted on an operating element. The actuating element comprises a rolling bearing provided with a rotating race and with a non-rotating race, the said bearing being able to be displaced radially with respect to the operating element to self-align with the clutch diaphragm, the non-rotating race comprising an inwardly-directed radial portion. The device comprises a means of axially securing the actuating element to the operating element. The device comprises a self-alignment member centred on the non-rotating race and provided with axially elastic elements, so that the said self-alignment member exerts, on the means of axial securing and on the non-rotating race, axial forces in opposite directions and keeps the non-rotating race in permanent axial contact with a radial bearing surface of the operating element.
Advantageously, the self-alignment member is centred on the inwardly-directed radial portion of the non-rotating race.
Advantageously, the means of axial securing comprises a locking washer. The locking washer may comprise a roughly radial annulus and a number of tabs extending inwards and capable of catching on a surface of the operating element.
In one embodiment of the invention, the self-alignment member comprises a portion for centring on the non-rotating race, and a radial portion in which the elastic elements are formed.
In one embodiment of the invention, the centring portion is axial and push-fitted onto the non-rotating race.
In one embodiment of the invention, the self-alignment member comprises a sealing portion which may form a narrow passage with the rotating race. The narrow passage may have dimensions independent of the position of the actuating element on the operating element.
The rotating race may comprise an inwardly-directed radial portion, the self-alignment member being arranged radially inside the rotating race, particularly inside the radial portion of the rotating race.
In an alternative, the elastic elements rest against a roughly radial surface of the means of axial securing.
In another alternative, the elastic elements rest against the radial portion of the non-rotating race.
The clutch bearing actuating element, according to one aspect of the invention, is intended to be mounted on an operating element to form a clutch bearing device. The actuating element comprises a rolling bearing provided with a rotating race, with a non-rotating race and with a row of rolling elements, the said rolling bearing being designed to be able to be displaced radially with respect to the operating element so as to self-align with the diaphragm of the clutch. The non-rotating race comprises an inwardly-directed radial portion. The actuating element comprises a self-alignment member centred on the non-rotating race and provided with axially elastic elements, coming from a radial portion of the said self-alignment member, at least some of the said elastic elements in their free state projecting axially with respect to the said radial portion.
The self-alignment member may on its periphery comprise an axial portion directed in the opposite direction to the axial portion push-fitted onto the non-rotating race, that is to say towards the diaphragm. The peripheral axial portion faces the bore of the rotating race. As the two races of the rolling bearing are perfectly concentric, a narrow radial passage of very small size may be provided between the peripheral axial portion of the self-alignment member and the bore of the rotating race. This narrow passage always remains identical regardless of the radial displacement of the rolling bearing as it self-aligns on the diaphragm.
The self-alignment tabs rest axially against the radial surface of an immobilizing and resting element attached to the operating element and forming a means of axial securing. The opposite face of the radial portion of the non-rotating race to the one which is in contact with the radial portion of the self-alignment member is in contact with a radial surface of the operating element, for example with a radial surface of a flange extending outwards.
The locking washer provided in its central region with tabs which are slightly oblique with respect to a radial plane and slightly flexible in the axial direction may be introduced onto a cylindrical portion of the operating element and lock itself thereon through a bracing effect. The radial force exerted by the tabs of the self-alignment member on the locking washer therefore, by reaction, keeps the radial portion of the non-rotating race of the bearing pressed against the radial bearing surface of the operating element. Of course, any other means of axial securing could be envisaged, provided it comprises a roughly radial surface for collaborating with the tabs of the self-alignment member.